Renin-angiotensin-aldosterone System Activation Research Articles

Oxidative Stress in Kidney Injury and Hypertension

Hypertension (HTN) is a major contributor to kidney damage, leading to conditions such as nephrosclerosis and hypertensive nephropathy, significant causes of chronic kidney disease (CKD) and end-stage renal disease (ESRD). HTN is also a risk factor for stroke and coronary heart disease. Oxidative stress, inflammation, and activation of the renin–angiotensin–aldosterone system (RAAS) play critical roles in causing kidney injury in HTN. Genetic and environmental factors influence the susceptibility to hypertensive renal damage, with African American populations having a higher tendency due to genetic variants. Managing blood pressure (BP) effectively with treatments targeting RAAS activation, oxidative stress, and inflammation is crucial in preventing renal damage and the progression of HTN-related CKD and ESRD. Interactions between genetic and environmental factors impacting kidney function abnormalities are central to HTN development. Animal studies indicate that genetic factors significantly influence BP regulation. Anti-natriuretic mechanisms can reset the pressure–natriuresis relationship, requiring a higher BP to excrete sodium matched to intake. Activation of intrarenal angiotensin II receptors contributes to sodium retention and high BP. In HTN, the gut microbiome can affect BP by influencing energy metabolism and inflammatory pathways. Animal models, such as the spontaneously hypertensive rat and the chronic angiotensin II infusion model, mirror human essential hypertension and highlight the significance of the kidney in HTN pathogenesis. Overproduction of reactive oxygen species (ROS) plays a crucial role in the development and progression of HTN, impacting renal function and BP regulation. Targeting specific NADPH oxidase (NOX) isoforms to inhibit ROS production and enhance antioxidant mechanisms may improve renal structure and function while lowering blood pressure. Therapies like SGLT2 inhibitors and mineralocorticoid receptor antagonists have shown promise in reducing oxidative stress, inflammation, and RAAS activity, offering renal and antihypertensive protection in managing HTN and CKD. This review emphasizes the critical role of NOX in the development and progression of HTN, focusing on its impact on renal function and BP regulation. Effective BP management and targeting oxidative stress, inflammation, and RAAS activation, is crucial in preventing renal damage and the progression of HTN-related CKD and ESRD.

Dose-exposure-response of CARDALIS® (benazepril/spironolactone) on the classical and alternative arms of the renin-angiotensin-aldosterone system in healthy dogs.

Benazepril exhibits a dose-dependent effect on biomarkers of the circulating renin-angiotensin-aldosterone system (RAAS) in dogs. To characterize the dose-exposure-response relationship of a fixed-dose combination product including benazepril and spironolactone (CARDALIS®) on RAAS biomarkers in dogs. Eighteen purpose-bred healthy beagle dogs. Three groups of 6 dogs received different doses of CARDALIS® for 14 days following induction of RAAS activation by feeding a low-sodium diet: (a) benazepril 0.25 mg/kg + spironolactone 2 mg/kg PO q24h (label dose); (b) benazepril 0.25 mg/kg + spironolactone 2 mg/kg PO q12h; or (c) benazepril 0.5 mg/kg + spironolactone 4 mg/kg PO q12h. Blood samples were collected at baseline and serial time intervals after CARDALIS® dosing to measure serum RAAS biomarkers and plasma concentrations of active drug metabolites. Time-weighted averages for serum RAAS biomarkers after CARDALIS® dosing at steady state were compared between dosage groups using Wilcoxon rank-sum testing. Compared to the label dose, the highest dose of CARDALIS® was associated with a 30% decrease in angiotensin II (P = .03), 94% increase in angiotensin 1-7 (P = .03), 71% decrease in surrogate activity of ACE (P = .002), and 116% increase in circulating aldosterone (P = .02). CARDALIS® was well-tolerated at all doses with no clinically relevant changes in renal values or serum electrolytes. The combined CARDALIS® product leads to dose-dependent alterations of RAAS metabolites. These results could help inform clinical trials in dogs with heart disease.

Angiotensin-converting-enzyme gene insertion-deletion polymorphism and renin angiotensin aldosterone system activity in different phenotypes of polycystic ovary syndrome

Polycystic ovary syndrome (PCOS) is a common condition. Its pathophysiology involves an interaction between genetic and environmental factors, resulting in different reproductive and metabolic subtypes. Genetic variation in the angiotensin converting enzyme (ACE) gene has been implicated in the pathophysiology of the syndrome. Our project aims to investigate the relationship between the ACE I/D (insertion/deletion) polymorphism and circulating levels of ACE activity, renin and aldosterone in PCOS. Patients and methodsPCOS and healthy donors were enrolled over 2 years. The Rotterdam criteria were used to segregate 4 phenotypes. Enrolled controls were matched to PCOS patients for body mass index. Clinical data were recorded and blood samples were taken for analysis of ACE I/D polymorphism and biochemical parameters. Hardy-Weinberg equilibrium evaluation, mean/median comparison and Spearman correlation were performed. ResultsA total of 102 women with PCOS and 107 controls were involved in the study. The most common polymorphism was ID, both in the control and PCOS groups. Renin levels in PCOS patients were positively correlated with luteinizing hormone (LH) and anti-mullerian hormone (AMH) in the ID genotype and with testosterone, free androgen index and insulin in the DD genotype. ConclusionThe ACE I/D variation may influence the pathophysiology of PCOS subtypes, together with an indirect relationship with renin. Our findings may provide valuable therapeutic insights into the management of PCOS, particularly regarding the potential need for ACE inhibitors or renin inhibitors tailored to ACE gene I/D genotypes or specific subtypes.

Epithelial Na + Channel Activation after Bile Duct Ligation with Mineralocorticoid Receptor Blockade.

Sodium and fluid retention in liver disease are classically thought to result from reduced effective circulating volume and stimulation of the renin-angiotensin-aldosterone system (RAAS). However, evidence of fluid retention in patients without RAAS activation suggests the involvement of additional mechanisms. In vitro, bile acids activate the epithelial Na+ channel (ENaC) found in the aldosterone-sensitive distal nephron. If this occurs in vivo, ENaC may become activated in liver disease even with antagonism of aldosterone signaling. To test this, we performed bile duct ligation to induce liver disease and increase circulating bile acids in mice given spironolactone to antagonize aldosterone signaling. We analyzed effects on blood, urine and body composition. We also determined the effects of taurocholic acid, a primary conjugated bile acid elevated in liver disease, on ion fluxes in microperfused rabbit collecting ducts. Bile duct ligation increased benzamil-sensitive natriuresis compared to sham, indicating ENaC activation. These effects were not explained by effects on ENaC expression, cleavage, or localization. Bile duct ligated mice also gained significantly more fluid than sham-operated animals. Blocking ENaC reversed fluid gains in bile duct ligated mice but had no effect in shams. In dissected collecting ducts from rabbits, which express ENaC, taurocholic acid stimulated net Na+ absorption. Our results provide experimental evidence for a novel aldosterone-independent mechanism for sodium and fluid retention in liver disease.

Unveiling the Interplay-Vitamin D and ACE-2 Molecular Interactions in Mitigating Complications and Deaths from SARS-CoV-2.

The interaction of the SARS-CoV-2 spike protein with membrane-bound angiotensin-converting enzyme-2 (ACE-2) receptors in epithelial cells facilitates viral entry into human cells. Despite this, ACE-2 exerts significant protective effects against coronaviruses by neutralizing viruses in circulation and mitigating inflammation. While SARS-CoV-2 reduces ACE-2 expression, vitamin D increases it, counteracting the virus's harmful effects. Vitamin D's beneficial actions are mediated through complex molecular mechanisms involving innate and adaptive immune systems. Meanwhile, vitamin D status [25(OH)D concentration] is inversely correlated with severity, complications, and mortality rates from COVID-19. This study explores mechanisms through which vitamin D inhibits SARS-CoV-2 replication, including the suppression of transcription enzymes, reduced inflammation and oxidative stress, and increased expression of neutralizing antibodies and antimicrobial peptides. Both hypovitaminosis D and SARS-CoV-2 elevate renin levels, the rate-limiting step in the renin-angiotensin-aldosterone system (RAS); it increases ACE-1 but reduces ACE-2 expression. This imbalance leads to elevated levels of the pro-inflammatory, pro-coagulatory, and vasoconstricting peptide angiotensin-II (Ang-II), leading to widespread inflammation. It also causes increased membrane permeability, allowing fluid and viruses to infiltrate soft tissues, lungs, and the vascular system. In contrast, sufficient vitamin D levels suppress renin expression, reducing RAS activity, lowering ACE-1, and increasing ACE-2 levels. ACE-2 cleaves Ang-II to generate Ang(1-7), a vasodilatory, anti-inflammatory, and anti-thrombotic peptide that mitigates oxidative stress and counteracts the harmful effects of SARS-CoV-2. Excess ACE-2 molecules spill into the bloodstream as soluble receptors, neutralizing and facilitating the destruction of the virus. These combined mechanisms reduce viral replication, load, and spread. Hence, vitamin D facilitates rapid recovery and minimizes transmission to others. Overall, vitamin D enhances the immune response and counteracts the pathological effects of SARS-CoV-2. Additionally, data suggests that widely used anti-hypertensive agents-angiotensin receptor blockers and ACE inhibitors-may lessen the adverse impacts of SARS-CoV-2, although they are less potent than vitamin D.

Sacubitril/Valsartan Combination Partially Improves Cardiac Systolic, but Not Diastolic, Function through β-AR Responsiveness in a Rat Model of Type 2 Diabetes

Cardiovascular complications are the major cause of diabetes mellitus-related morbidity and mortality. Increased renin–angiotensin–aldosterone system activity and decreased β-adrenergic receptor (β-AR) responsiveness contribute to diabetic cardiac dysfunction. We evaluated the effect of sacubitril/valsartan (neprilysin inhibitor plus angiotensin receptor antagonist combination) and valsartan treatments on the diabetic cardiac function through β-AR responsiveness and on protein expression of diastolic components. Six-week-old male Sprague Dawley rats were divided into control, diabetic, sacubitril/valsartan (68 mg/kg)-, and valsartan-treated (31 mg/kg) diabetic groups. Diabetes was induced by a high-fat diet plus low-dose streptozotocin (30 mg/kg, intraperitoneal). After 10 weeks of diabetes, rats were treated for 4 weeks. Systolic/diastolic function was assessed by in vivo echocardiography and pressure–volume loop analysis. β-AR-mediated responsiveness was assessed by in vitro papillary muscle and Langendorff heart experiments. Protein expression of sarcoplasmic reticulum calcium ATPase2a, phospholamban, and phosphorylated phospholamban was determined by Western blot. Sacubitril/valsartan improved ejection fraction and fractional shortening to a similar extent as valsartan alone. None of the treatments affected in vivo diastolic parameters or the expression of related proteins. β1-/β2-AR-mediated responsiveness was partially restored in treated animals. β3-AR-mediated cardiac relaxation (an indicator of diastolic function) responses were comparable among groups. The beneficial effect of sacubitril/valsartan on systolic function may be attributed to improved β1-/β2-AR responsiveness.

Characterization of the circulating markers of the renin-angiotensin-aldosterone system in telmisartan- or enalapril-treated dogs with proteinuric chronic kidney disease.

Effects of the renin-angiotensin-aldosterone system (RAAS) inhibitors enalapril and telmisartan on circulating RAAS in dogs with proteinuric chronic kidney disease (pCKD) are undescribed. To characterize the RAAS in untreated dogs with pCKD compared to healthy, life-stage- and sex-matched controls, and in dogs with pCKD after 30 days of treatment with enalapril or telmisartan. Dogs with pCKD (n = 36) and healthy controls (n = 20). Retrospective study of banked samples and previously collected data. Day 0 serum equilibrium concentrations of angiotensin I, II, III, IV, 1-5, and 1-7, and aldosterone, and urinary aldosterone-to-creatinine ratio (UACR) from pCKD dogs were compared to values on day 30 of treatment with enalapril (0.5 mg/kg PO q12) or telmisartan (1 mg/kg PO q24h) and to those of healthy dogs. Data were analyzed using linear mixed models. Compared with healthy dogs, pCKD dogs had significantly higher Ang I, III, 1-5, and 1-7 concentrations, and UACR. Relative to pretreatment values, day 30 Ang II concentrations were significantly increased and decreased in telmisartan- and enalapril-treated pCKD dogs, respectively (both P < .001). Mean (95% confidence interval) percentage change from pretreatment value in serum Ang 1-7 concentration was significantly greater in telmisartan- (753% [489%-1134%]) versus enalapril-treated (149% [69%-268%]) dogs (P < .001). Serum aldosterone decreased with treatment (P = .02 for enalapril, P < .001 for telmisartan), with no difference between groups at day 30. Circulating RAAS activity is higher in dogs with pCKD. Compared with enalapril, treatment with telmisartan caused significantly greater increases in the presumed beneficial peptide Ang 1-7.

Sex-Specific Associations of Aldosterone and Renin with Body Composition: A Population-Based Cohort Study.

Renin-angiotensin-aldosterone system (RAAS) activation is closely linked to obesity; however, the sex-specific associations between RAAS activity and body composition among individuals without obesity are not well understood. To investigate the associations of aldosterone and renin with body composition according to sex in the general population. Population-based cohort study. Québec (Canada). Adults aged 40-69 years enrolled to CARTaGENE between 2009 and 2010 (N=3,687). Plasma aldosterone and renin concentrations. Body composition assessed via anthropometrics (waist circumference and waist-to-hip ratio), bioelectrical impedance (lean body mass, fat mass, and muscle mass), and cardiac magnetic resonance imaging (epicardial and pericardial adipose tissue volumes). The mean (SD) age and body mass index were 55 (8) years and 27.3 (4.8) kg/m2, respectively. Among males, higher aldosterone and renin were associated with increased waist circumference, increased waist-to-hip ratio, increased fat mass, decreased lean body mass, and decreased muscle mass (p<0.05). Aldosterone (p=0.02), but not renin (p=0.43), was associated with increased ectopic cardiac adiposity in males. In contrast, higher renin (p<0.05), but not aldosterone (p≥0.05), was associated with increased waist circumference, increased waist-to-hip ratio, and increased cardiac adiposity in females. Among females, higher renin and aldosterone were associated with increased fat mass (p<0.05) but were not associated with lean body mass or muscle mass (p≥0.05). All aforementioned associations were independent of body weight. Independent of body weight, increased RAAS activity is associated with unfavorable differences in body composition; however, the strength and pattern of association varies by sex.

Advanced progress of the relationship between renin-angiotensin-aldosterone system inhibitors and cancers.

Hypertension and cancers are the most common causes of death in humans, as well as common co-diseases among elderly population. Studies have shown that hypertension is associated with carcinogenesis. The renin-angiotensin-aldosterone system (RAAS) is a crucial regulatory system of blood pressure, fluid, and electrolyte homeostasis, which plays an essential role in the pathogenesis of hypertension, whose mechanism is relatively clear. Studies have indicated that RAAS also widely exists in cancer tissues of different systems, which can affect the risk of cancers by stimulating cancer angiogenesis, participating in cancer-related oxidative stress, and regulating cancer-related immunity. Therefore, inhibiting RAAS activity seems beneficial to decreasing the risk of cancers. As one of the most commonly used antihypertensive drugs, RAAS inhibitors have been widely used in clinical practice. However, the conclusions of clinical studies on the relationship between RAAS inhibitors and cancers are not entirely consistent, which has been widely concerned by clinicians. The latest findings suggest that while RAAS inhibitors may reduce the risk of digestive cancers, respiratory cancers, urological cancers, gynecological cancers, and skin cancers, ACEIs may increase the risk of lung cancer, endometrial cancer, basal cell carcinoma, and squamous cell carcinoma. This article comprehensively reviews animal experiments, clinical studies, and meta-analyses on the relationship between RAAS inhibitors and cancers, to provide references for related studies in the future.

Abstract We140: Age-Dependent miR-34a and AGTRAP Cross-Modulation: a Novel Mechanism of Vascular Aging

Background: Renin-Angiotensin Aldosterone System (RAAS) activation plays a central role in vascular aging, leading to structural and functional alterations including vascular smooth muscle cell (VSMC) proliferation, migration and secretion of extracellular matrix and inflammatory molecules. The age-associated increase in Angiotensin II (Ang II) expression enhances AT1-receptor activity and determinates a pro-fibrotic and pro-inflammatory phenotype. Further, miR-34a expression is modulated by aging and increases in different tissues, including the mouse aorta, but no direct miR-34a target has been identified in the RAAS pathway that sustains age-dependent increase of pro-inflammatory signaling. Aims: The aim of our study is to evaluate the potential interaction between miR-34a and RAAS signaling in VSMCs. Methods and Results: miR-34a expression exhibited an age-dependent increase in Rhesus Monkey (8- to 26-year-old) and rat central arteries (8- and 30-month-old). In silico analysis indicated that AT1R-associated protein (AGTRAP), a negative modulator of AT1R signaling, is a potential miR-34a target suggesting that the age-dependent increase in miR-34a in the arterial vascular wall may decrease AGTRAP expression in arterial VSMC. Ang II enhanced miR-34a expression in 30-month-old rat and in human aorta SMCs (HASMCs), whereas AGTRAP and Sirtuin-1 (SIRT1) mRNA and protein level decreased. Immunohistochemistry analysis showed a decrease of AGTRAP in 18-month-old miR-34a knock-out mice compared to 2-month-old mice. By luciferase assay, we demonstrated that AGTRAP is a direct miR-34a target. Moreover, AGTRAP and SIRT1 decreased in HASMCs infected with miR-34a-encoding lentivirus and this effect was partially rescued in AGTRAP/miR-34a co-infected cells. Finally, pro-inflammatory genes IL-6, COX-2, MCP-1 and MFG-E8 expression was upregulated in Ang II-treated and miR-34a overexpressing HASMCs, and this effect was abolished in AGTRAP/miR-34a co-transfected cells. Conclusions: Our results show cross-modulation between miR-34a and AGTRAP. MiR-34a targeting AGTRAP increases the expression of pro-inflammatory molecules in VSMCs and represents a novel mechanism that modulates RAAS signaling in vascular aging. Statement: This research was supported in part by the Intramural Research Program of the NIH, National Institute on Aging.

Systemic hemodynamics and pediatric lung disease: mechanistic links and therapeutic relevance.

Chronic lung disease, also known as bronchopulmonary dysplasia, affects thousands of infants worldwide each year. The impact on resources is second only to bronchial asthma, with lung function affected well into adolescence. Diagnostic and therapeutic constructs have almost exclusively focused on pulmonary architecture (alveoli/airways) and pulmonary hypertension. Information on systemic hemodynamics indicates major artery thickness/stiffness, elevated systemic afterload, and/or primary left ventricular dysfunction may play a part in a subset of infants with severe neonatal-pediatric lung disease. Understanding the underlying principles with attendant effectors would aid in identifying the pathophysiological course where systemic afterload reduction with angiotensin-converting enzyme inhibitors could become the preferred treatment strategy over conventional pulmonary artery vasodilatation.NEW & NOTEWORTHY Extremely preterm infants are at a higher risk of developing severe bronchopulmonary dysplasia. In a subset of infants, diuretic and pulmonary vasodilator therapy is ineffective. Recent information points toward systemic hemodynamic disease (systemic arterial stiffness and left ventricular dysfunction) as a contributor via back-pressure changes. Mechanistic links include heightened renin angiotensin aldosterone system activity, inflammation, and oxygen toxicity. Angiotensin-converting enzyme inhibition may be operationally more suited compared with induced pulmonary artery vasodilatation.

Modern approaches to understanding pathogenetic link between arterial hypertension and renal failure from the point of view of evidence based medicine

Background: Renal failure and arterial hypertension are critical global health issues affecting millions worldwide. Hypertension, affecting over 1.13 billion individuals, is a significant risk factor for cardiovascular and renal diseases. Chronic kidney disease (CKD), affecting approximately 10% of the global population, significantly impacts morbidity, mortality, and socioeconomic wellbeing. The reciprocal relationship between hypertension and renal failure exacerbates these conditions, creating a detrimental cycle of worsening health. Methods and Materials: This study employs a comprehensive review of epidemiological data, pathophysiological mechanisms, and evidence-based management strategies. The research focuses on the bidirectional link between arterial hypertension and renal failure, analyzing the shared pathophysiological pathways such as endothelial dysfunction, inflammation, oxidative stress, and the activation of the renin-angiotensin-aldosterone system (RAAS). Data from various clinical trials and epidemiological studies are synthesized to propose effective treatment and management plans. Results: The findings indicate a strong reciprocal correlation between arterial hypertension and renal failure. Hypertension is prevalent in over 85% of CKD patients, and individuals with hypertension have a significantly higher risk of developing CKD. Shared pathophysiological mechanisms, such as endothelial dysfunction, inflammation, oxidative stress, and RAAS activation, contribute to the progression and worsening of both conditions. Effective management requires addressing these common mechanisms through evidence-based treatments like RAAS inhibitors and lifestyle modifications. Conclusion: The study underscores the need for integrated management strategies targeting both arterial hypertension and renal failure. Early detection, prevention, and comprehensive treatment approaches are crucial for mitigating the health and socioeconomic impacts of these interrelated diseases. Future research should focus on novel therapeutic strategies and personalized medicine to improve patient outcomes and reduce the global healthcare burden.

Fluid Restriction for Patients with Heart Failure: Current Evidence and Future Perspectives.

Fluid restriction has long been believed to benefit patients with heart failure by counteracting the activated renin-angiotensin aldosterone system and sympathetic nervous activity. However, its effectiveness remains controversial. In this paper, we summarized the current recommendations and reviewed the scientific evidence on fluid restriction in the setting of both acute decompensated heart failure and compensated heart failure. While a recent meta-analysis demonstrated the beneficial effects of fluid restriction on both all-cause mortality and hospitalization compared to usual care, several weaknesses were identified in the assessment of the methodological quality of the meta-analysis using AMSTAR 2. Further randomized controlled trials with larger sample sizes are needed to elucidate the benefits of fluid restriction for both clinical outcomes and patient-reported outcomes in patients with heart failure.

Impact of RAAS Receptors and Membrane-Bound Transporter System in the Left Ventricle during the Long-Term Control of Hypertension.

The Renin-Angiotensin-Aldosterone System (RAAS) has been implicated in systemic and neurogenic hypertension. The infusion of RAAS inhibitors blunted arterial pressure and efficacy of use-dependent synaptic transmission in sympathetic ganglia. The current investigation aims to elucidate the impact of RAAS-mediated receptors on left ventricular cardiomyocytes and the role of the sarcolemma-bound carrier system in the heart of the hypertensive transgene model. A significant increase in mRNA and the protein expression for angiotensin II (AngII) receptor subtype-1 (AT1R) was observed in (mREN2)27 transgenic compared to the normotensive rodents. Concurrently, there was an upregulation in AT1R and a downregulation in the MAS1 proto-oncogene protein receptor as well as the AngII subtype-2 receptor in hypertensive rodents. There were modifications in the expressions of sarcolemma Na+-K+-ATPase, Na+-Ca2+ exchanger, and Sarcoendoplasmic Reticulum Calcium ATPase in the transgenic hypertensive model. These observations suggest chronic RAAS activation led to a shift in receptor balance favoring augmented cardiac contractility and disruption in calcium handling through modifications of membrane-bound carrier proteins and blood pressure. The study provides insight into mechanisms underlying RAAS-mediated cardiac dysfunction and highlights the potential value of targeting the protective arm of AngII in hypertension.

The relationship between adipose tissue RAAS activity and the risk factors of prediabetes in different ethnicities: A protocol for a systematic review and meta-analysis.

The incidence and prevalence of prediabetes has become a global concern. The risk factors of prediabetes, such as insulin resistance, adiposity, lipotoxicity and obesity, in conjunction with the alteration of the renin-angiotensin-aldosterone system (RAAS), have been positively correlated with the high morbidity and mortality rate. Thus, this systematic review seeks to establish the relationship between the risk factors of prediabetes, namely insulin resistance adiposity, lipotoxicity, obesity and the RAAS. Therefore, a synthesis of these risk factors, their clinical indicators and the RAAS components will be compiled in order to establish the association between the RAAS alteration and obesity in prediabetic patients. This protocol for a systematic review was developed in compliance with the Preferred Reporting Items for Systematic Review and Meta-Analysis Protocols (PRISMA-P) standards. This will be accomplished by searching clinical Medical Subject Headings categories in MEDLINE with full texts, EMBASE, Web of Science, PubMed, Cochrane Library, Academic Search Complete, ICTRP and ClinicalTrial.gov. Reviewers will examine all of the findings and select the studies that meet the qualifying criteria. To check for bias, the Downs and Black Checklist will be used, followed by a Review Manager v5. A Forrest plot will be used for the meta-analysis and sensitivity analysis. Furthermore, the strength of the evidence will be assessed utilizing the Grading of Recommendations Assessment, Development, and Evaluation procedure (GRADE). The protocol has been registered with PROSPERO CRD42022320252. This systematic review and meta-analysis will include published randomized clinical trials, observational studies and case-control studies from the years 2000 to 2022.

Natriuretic peptide pathways in heart failure in the context of the analysis of the mechanism of action and potential usages of sacubitril/valsartan

Natriuretic peptide pathways in heart failure in the context of the analysis of the mechanism of action and potential usages of sacubitril/valsartan

Angiotensin Receptor-Neprilysin Inhibitor Suppresses Renin-Angiotensin-Aldosterone System Activation After Cardiac Surgery Using Cardiopulmonary Bypass.

Sacubitril/valsartan, being both a neprilysin inhibitor and angiotensin receptor blocker, exhibits a renin-angiotensin-aldosterone system (RAAS) inhibitory effect. However, no study has investigated the administration of sacubitril/valsartan in patients early after surgery using cardiopulmonary bypass. This was a prospective observational study of 63 patients who underwent open heart surgery and were treated with sacubitril/valsartan. No serious adverse events occurred. Among the 63 patients, sacubitril/valsartan was discontinued in 13 due to hypotension (n=10), renal dysfunction (n=2), and dizziness (n=1). Atrial natriuretic peptide concentrations increased significantly from Day 3 of treatment (P=0.0142 vs. Postoperative Day 1) and remained high thereafter. In contrast, plasma renin activity was significantly suppressed from Day 3 onwards (P=0.00206 vs. Postoperative Day 1). A decrease in creatinine concentrations and an increase in the estimated glomerular filtration rate were observed on Day 3; this improvement in renal function was not observed in the historical control group, in which patients did not receive sacubitril/valsartan. New postoperative atrial fibrillation was less frequent in the study group compared with the historical control (12.7% vs. 38.0%; P=0.0034). Sacubitril/valsartan administration was safe immediately after open heart surgery in patients without postoperative hypotension. It enhanced serum atrial natriuretic peptide concentrations and suppressed RAAS activation.

Primary Role of the Kidney in Pathogenesis of Hypertension.

Previous transplantation studies and the concept of 'nephron underdosing' support the idea that the kidney plays a crucial role in the development of essential hypertension. This suggests that there are genetic factors in the kidney that can either elevate or decrease blood pressure. The kidney normally maintains arterial pressure within a narrow range by employing the mechanism of pressure-natriuresis. Hypertension is induced when the pressure-natriuresis mechanism fails due to both subtle and overt kidney abnormalities. The inheritance of hypertension is believed to be polygenic, and essential hypertension may result from a combination of genetic variants that code for renal tubular sodium transporters or proteins involved in regulatory pathways. The renin-angiotensin-aldosterone system (RAAS) and sympathetic nervous system (SNS) are the major regulators of renal sodium reabsorption. Hyperactivity of either the RAAS or SNS leads to a rightward shift in the pressure-natriuresis curve. In other words, hypertension is induced when the activity of RAAS and SNS is not suppressed despite increased salt intake. Sodium overload, caused by increased intake and/or reduced renal excretion, not only leads to an expansion of plasma volume but also to an increase in systemic vascular resistance. Endothelial dysfunction is caused by an increased intracellular Na+ concentration, which inhibits endothelial nitric oxide (NO) synthase and reduces NO production. The stiffness of vascular smooth muscle cells is increased by the accumulation of intracellular Na+ and subsequent elevation of cytoplasmic Ca++ concentration. In contrast to the hemodynamic effects of osmotically active Na+, osmotically inactive Na+ stimulates immune cells and produces proinflammatory cytokines, which contribute to hypertension. When this occurs in the gut, the microbiota may become imbalanced, leading to intestinal inflammation and systemic hypertension. In conclusion, the primary cause of hypertension is sodium overload resulting from kidney dysregulation.

The emerging concept of glycocalyx damage as the trigger of heart failure onset and progression

The suppression of adrenergic and renin-angiotensin-aldosterone system (RAAS) activity, exaggerated due to hypoperfusion-related hypoxia and/or sodium retention, is crucial for drugs’ efficacy in heart failure (HF). Both, insufficient oxygenation and excess sodium impair the glycocalyx-dependent microcroperfusion and peripheral metabolism, therefore enhancing the adrenergic and RAAS activity. The local renal and pulmonary RAAS activity and hypoxia increase sodium retention. Interstitial sodium accumulation activates interstitial inflammation and coagulation disorders that further diminish glycocalyx-supported microperfusion and peripheral metabolism. The main trigger of glycocalyx damage in reduced ejection fraction (EF) HF is hypoxia; whereas, in HF preserved EF sodium retention prevails; both stimulate left ventricular (LV) cardiac output (CO), however, impair microperfusion and metabolic heat production. Infrared-dependent, surface-induced flow (SIF) and diamagnetic properties of oxygenated haemoglobin; both improve non-Newtonian blood flow. Therefore, the temperature-driven SIF augments the deoxygenated erythrocytes' flow, while the pulmonary oxygenation of haemoglobin, by diamagnetic properties, enables frictionless erythrocytes’ flow in the oxygenated blood compartments complementing the cardiac function in HF.

Protective Role of Taurine on Rat Offspring Hypertension in the Setting of Maternal Chronic Kidney Disease.

Taurine is a natural antioxidant with antihypertensive properties. Maternal chronic kidney disease (CKD) has an impact on renal programming and increases the risk of offspring hypertension in later life. The underlying mechanisms cover oxidative stress, a dysregulated hydrogen sulfide (H2S) system, dysbiotic gut microbiota, and inappropriate activation of the renin-angiotensin-aldosterone system (RAAS). We investigated whether perinatal taurine administration enables us to prevent high blood pressure (BP) in offspring complicated by maternal CKD. Before mating, CKD was induced through feeding chow containing 0.5% adenine for 3 weeks. Taurine was administered (3% in drinking water) during gestation and lactation. Four groups of male offspring were used (n = 8/group): controls, CKD, taurine-treated control rats, and taurine-treated rats with CKD. Taurine treatment significantly reduced BP in male offspring born to mothers with CKD. The beneficial effects of perinatal taurine treatment were attributed to an augmented H2S pathway, rebalance of aberrant RAAS activation, and gut microbiota alterations. In summary, our results not only deepen our knowledge of the mechanisms underlying maternal CKD-induced offspring hypertension but also afford us the impetus to consider taurine-based intervention as a promising preventive approach for future clinical translation.